Which of the following is characteristic of aircraft in the heavy weight class?

The characteristic of aircraft in the heavy weight class is defined primarily by their takeoff weight, and option C correctly identifies this key aspect. Heavy aircraft are typically those with takeoff weights of 300,000 pounds or more. This classification is essential for air traffic control because heavier aircraft have different flight dynamics, performance characteristics, and require different spacing and consideration during takeoff and landing due to their impact on airport traffic.

In contrast, other options do not align with the definition of the heavy weight class. The maximum certified takeoff weight of 100,000 pounds mentioned in another option falls below the threshold required to classify an aircraft as heavy. Operating speeds of 200-300 knots can apply to various aircraft, including medium and light, and do not specifically indicate a heavy classification. Lastly, the mention of typically single-engine aircraft does not apply to heavy weight classes, which are commonly multi-engine, allowing for greater weight capacity and performance. Understanding these distinctions is critical for effective air traffic management and safety.